1. Field of the Invention
The present invention relates to communications, and more particularly to optimizing re-authentication in EAP-AKA.
2. Background of Invention
A wireless network generally includes many wireless nodes and users trying to gain access to a network. The primary means for controlling access include network access servers (“NAS”) and authentication servers. A NAS provides access to the network. A primary authentication server, such as an authentication, authorization, accounting (AAA) server, provides centralized authentication services to a NAS for authenticating client devices before they are granted access to the network. In typical installations, the devices and users connect through the NAS to obtain access to a network (e.g., the Internet) via some form of wireless connection. The authentication server is typically a RADIUS (Remote Authentication Dial-In User Service) or Diameter server.
EAP-AKA (Extensible Authentication Protocol-Authentication and Key Agreement) is a protocol for authenticating subscribers using a USIM (Universal Mobile Telecommunications System (UMTS) Subscriber Identity Module) who wish to connect to a wireless network. EAP-AKA typically requires an AAA server to retrieve key material from a HLR/HSS (Home Location Register/Home Subscriber Server). Network operators are very sensitive to the additional load on the HLR/HSS as a result of this interaction. EAP-AKA employs a mechanism called Fast Re-authentication to eliminate the need to retrieve key material from the HLR/HSS on every subscriber authentication. Fast Re-authentication uses a temporary identifier issued by the AAA on every successful authentication. The temporary identifier is stored on the client device for presentation to the AAA server on the next authentication. Unfortunately, the Fast Re-authentication mechanism requires the AAA server to store session state information. A resilient implementation also requires this session state information to be replicated on backup AAA servers. Fast Re-authentication is described in depth in “RFC 4187: Extensible Authentication Protocol Method for 3rd Generation Authentication and Key Agreement (EAP-AKA)” by the Internet Engineering Task Force (IETF), the disclosure of which is hereby incorporated by reference.
What is needed are systems and methods that provide the benefits of the Fast Re-Authentication mechanism while providing greater flexibility and a lower overhead.